GRANT=R556222-01 This research is directed towards improving hearing aid fitting for older adults. Despite substantial improvements in hearing aid technology, the hearing aid take-up rate, and the satisfaction with fitted hearing aids has not improved in the last decade. This is partly due to a failure by the research community to produce and disseminate updated fitting methods that facilitate the ability of practitioners to capitalize on the potential of existing new technologies. The two experiments in this proposal will produce guidelines to assist clinicians to make scientifically based decisions about amplification needs, based on the results of tests conducted before the fitting. The first experiment bridges the gap between laboratory research and clinical in selection of high frequency gain characteristic. Recent studies have demonstrated that, for some individuals with high-frequency hearing loss, high frequency amplification is actually detrimental rather than helpful. There is a pressing need for a clinically practical method that would validly identify patients for whom high-frequency gain is contraindicated. The study assesses the prevalence of such patients, and evaluates two new clinical procedures that have been developed to identify these individuals. The two procedures are used to identify experimental and control groups comprising 20 pairs of subjects. Each subject is fitted with a hearing aid that allows comparison of two amounts of high-frequency gain. Subjects undergo laboratory testing and a field trial to determine which high-frequency gain setting is better. Results show whether the two new clinical procedures yield accurate prediction of optimal high-frequency gain. The second experiment explores the indications for bilateral (binaural) hearing aid fittings for older adults with bilateral hearing loss. About 20 to 30% of bilaterally fitted individuals actually elect to wear only one hearing aid. For these individuals, resources allocated to hearing aid purchase would have been more effectively used for alternate rehabilitation methods. It is not clear why some patients prefer one hearing aid over two, or which patients will fall into this category. This study evaluates outcomes of 100 bilateral hearing aid fittings over a three-month period. Logistic regression is used to develop a model in which binaural summation, binaural integration, binaural interference, and attitudes towards hearing aids and hearing loss are combined to predict which individuals will ultimately prefer to use one hearing aid rather than two.